A new in situ technique, the InEx, was used to cleanly sample the water inhaled and exhaled by sponges, bivalves and benthic ascidians in the coral reef of Eilat, The Red Sea. Feeding rates on phytoplankton and bacteria were estimated based on the decrease in their concentrations in the exhaled, compared with the inhaled water and on direct measurements of the animal's pumping rates. Concentrations of ultraphytoplankton and bacteria were measured by a flow cytometer, while DOC was measured using the HTC method. Diet composition, filtration efficiency, and pumping rates were nearly uniform within a taxon but considerably vary between taxa. Bivalves and ascidians selectively ingested Prochlorococcus (44-65% removal efficiency) but not heterotrophic bacteria of a similar size. Synechococcus was selected for by all taxa examined (55-94%). The carbon flux to the benthic community due to the animals' feeding on ultraplankton was of the same magnitude estimated for the feeding on zooplankton by fish, corals, and other invertebrates together. Our preliminary DOC measurements suggested that dissolved organic matter was removed by some of the taxa examined. Additional samples will have been completed prior to the presentation. The results and their ecological implications will be discussed in the presentation.